The subject matter to which this invention pertains is in the field of kinematic and robotic mechanisms. Wheels, casters and rollers are used in a wide variety of applications to transport equipment and people between stations and locations. This utility of the wheel indeed relies on gravity or some other discrete force to hold the vehicle to the surface on which it travels. However, in certain modes of transportation, gravity is nullified or even negated by an equivalent or overcoming acceleration or force. An example of equivalence would be the case in space transport, where Earth's gravity is measured in micro-units. Overcoming or negating gravity can be achieved when enough lifting or tilting force is exerted on the vehicle to overcome its own weight, causing instability. Several examples of this are; 1) a commercial passenger aircraft refreshment cart lifting from the aisle floor during an extreme maneuver or sudden loss of elevation, 2) an ambulance gurney lifting from or sliding across the ambulance floor because of an unexpected maneuver, 3) a mobile tooling fixture braking or stopping suddenly and tipping over because of a high center-of-gravity, 4) the front wheels of a car lifting off the road because of the torque applied at the rear wheels.
Presently, structures that require frictionless anti-lift and anti-tilt ability rely on using a track with dual rollers. This type of design requires that the primary wheels placed on the track be equipped with additional internal track wheels that are connected through a slot opening in the track. The two wheels travel together, with the primary wheels supporting the weight of the vehicle and the secondary wheels running along the underside surface of the track preventing the primary wheel from lifting off the track if a load reversal occurs. Although this design is adequate for retaining the vehicle to the track, the vehicle cannot be removed from the track without disassembly of the entire wheel carriage assembly or movement of the vehicle to a designated end of the track. Present tracked wheel designs are therefore, not portable. The vehicle must remain on its original track until disassembled or removed at the end of the track. A tracked wheel that features an integral release mechanism allowing it to be portable, namely, moved from one track to another track or simply set free from the confines of the track, would be of particular use on vehicles subject to reversing or lifting forces.
Considering the issue of safety, the aircraft refreshment or food cart and ambulance gurney examples are used because these pose particular risks for passenger transportation. During flight, the cart is pushed along the aisle, fully susceptible to a sudden mishap that would cause it to lift off the floor. The cart may then become a massive projectile liable to cause considerable injury to passengers onboard or damage to the aircraft.
In the instance of an ambulance gurney, the gurney can lift from the vehicle floor and dislodge critical instrumentation or medicinal tubes attached to the patient. In accordance with this invention, a caster device that locks the cart or gurney to the floor while in service, but may be disengaged and returned to a safe stowage location after use, solves these problems. Moreover, movement of objects or vehicles in the weightless environment of extraterrestrial space, in certain cases, requires restraint to the primary spacecraft. An example of this is a mobile pallet or service vehicle used for maintenance or inspection of an external surface of an orbiting spacecraft. This invention, a portable tracked wheel, would assist the extravehicular activity by allowing the astronaut/operator to remove a stowed maintenance cart from one section of the spacecraft and attach it to the track to be rolled and utilized at a different area of the spacecraft. In addition, acceleration sleds, test apparatus and possibly aircraft landing gear may utilize this invention for its portability. Quick and easy removal, refurbishment and replacement of worn-out or damaged test fixtures that require stabilized mobility can be accomplished by means of this device. Launch and recovery of aircraft on unstable platforms can be accomplished with a robust and robotic configuration of this invention.
It is thus one object of the present invention is to fulfill the need for a portable tracked wheel assembly. This device will allow easy, portable removal and engagement between tracked vehicle motion and free motion outside of the track restraint. Accordingly, the operator or robot is afforded a simple push-tab to engage and disengage the anti-lift feature of the design. A wide variety of uses including safety, maintenance and assembly line processes can be greatly enhanced by this invention. Other objects will become clear upon a reading of the specification.